Previous studies about the relationship between alcohol drinking contexts and drinking-related problems among young people are limited in that they have (1) focused primarily on young adult college students, (2) relied on retrospective recall of past events and behaviors, (3) not focused on separating out the unique effects of drinking location (e.g. beach, or house party) and setting characteristics (e.g. group size, gender composition), (4) typically focused on a small number of drinking contexts and drinking-related problems (e.g. aggression or risky sex only), and (5) been cross-sectional and have not studied dynamic relationships over time. These shortcomings limit our understanding of the contribution of drinking context to alcoholrelated problems among youth and what approaches can be used to target high risk drinking contexts. The proposed research addresses these shortcomings by studying drinking contexts, alcohol consumption, and alcohol-related problems among adolescents and obtaining longitudinal real-time data to reduce recall errors and better capture the dynamic relations among drinking contexts, consumption, and problems. Specifically, the aims of the proposed study are: (1) to identify and describe youth drinking contexts and setting characteristics; (2) to examine the dynamic relationship between youth drinking contexts and alcohol-related problems; and (3) to study the independent contribution of drinking location and setting characteristics and the potential interaction among them in predicting youth alcohol-related problems. A mixed-method approach with telephone surveys and ecological momentary assessments (EMA) will be used. Telephone survey data will be obtained at two time points from youth (N = 1,200) in 24 mid-sized California cities. Wave 1 of the survey will allow to initially investigate drinking contexts, consumption, and problems cross-sectionally, as well as to identify drinking and non-drinking youth (N = 216) for an in-depth study using EMA to obtain real-time data about alcohol use, drinking locations and contexts, and alcoholrelated problems. The EMA study will allow us to (1) investigate the dynamic relationships among drinking contexts, consumption, and problems, and (2) inform the development of a comprehensive drinking contexts instrument for Wave 2. Wave 2 of the survey will allow us to investigate the relationships between context and alcohol-related problems at the population level. The longitudinal design will also allow us to investigate changes across time in adolescents' drinking contexts and whether the selection of drinking contexts differs across periods of adolescent development. Results from the proposed study will guide prevention efforts in targeting high risk drinking contexts.